1. Field of the Invention
The present invention relates to polyaminocarboxylates that are cross-linked anionic polyelectrolytes (CAPE), and particularly to cross-linked polyaminocarboxylates for the removal of metal ions from aqueous solutions.
2. Description of the Related Art
Removal of toxic metal ions is a matter of great importance due to their negative effects on the environment and human health. Nonbiodegradable Cu2+ ions, in typical concentrations of several thousand ppm to less than 1 ppm, are produced as waste in various chemical industries, such as smelting, mining, printed circuit board manufacturing, electroplating, wire drawing, copper polishing, and paint manufacturing. The accumulation of copper in the human body can cause a variety of diseases and disorders. High intake of copper can be fatal. A concentration of 1.3 ppm can cause immediate effects on infants and adults in the form of vomiting, diarrhea, nausea; at higher concentrations. For infants, it can cause liver and kidney damage. According to WHO standards, the maximum allowable concentration of copper in drinking water is 0.2 mg/L, while it is 0.2 and less than 2 ppm for agricultural irrigation and pond fish farming, respectively. In order to protect humans and the environment, it is of utmost importance to remove copper ions from the environment.
Various techniques, such as adsorption, precipitation, dialysis, ion exchange, reverse osmosis, and extraction, have been developed in the past for the removal of metal contaminants from water resources. One of the most attractive among these techniques is the adsorption process due to the availability of different types of low-cost and environmentally friendly adsorbents. Inorganic/organic polymer hybrid adsorbents have been widely investigated. Their efficacy in metal ion removal is attributed to the formation of a stronger chemical bonding between Mn+ and, for instance, amine motifs in the hybrid materials. Recently, researchers have focused on the syntheses of zwitterionic cross-linked inorganic/organic hybrid materials for the removal of heavy metal ions via electrostatic effects.
There are many sorbent materials to remove larger concentration of metal ions. However, it remains challenging to develop new materials for removing copper ions at ppb-levels. Thus, cross-linked polyaminocarboxylates for the removal of metal ions from aqueous solutions solving the aforementioned problems is desired.